Wanted to throw this idea out to the experts, so please humor me if you will...
Two things lacking from my reviews have been:
- PWM readings (building audio cable connected to solar cell and will use a PC soundcard oscilloscope program
- Lumens measurement. While I can do a ceiling bounce, there are usually too many factors introduced (beam shape/intensity chief amongst them)
For the latter, I've been meaning to build an IS but don't like the idea that there would not be a stable platform/holder for the light while I'm taking measurements (especially for runtime logging). Also, based upon what I've read, I felt tweaking the baffle has been one of the trickiest parts to calibrating it properly. So I came up with this idea based on the following criteria:
- must accomodate bezel head up to 4" in diam
- allow consistent repeatable measurements
- provide stable platform for light to rest on while doing runtime / logging and light must be exposed to allow fan to cool it
- not be affected by ambient lighting while logging is in progress
- no fiddling w/a baffle
- simple to build w/easily sourced parts
- reasonably budget friendly
- allow light sensor to be easily removed for other measurements
- easy for others to build/reproduce
I've read about the PVC U-pipe idea but decided to add an extra 90deg. elbow to further reduce the likelihood of any direct reflection making it to the light sensor and ended up with this:
Total parts used cost $34.40 before taxes:
- 3 x 4" 90deg. PVC elbows
- 1 x 4" -> 3" step down adapter
- 1 x 3" -> 1.5" stepd down adapter/cap
The entire contraption will be strapped/bolted onto a wood base. The end where I'm shining the light into will have a glass/plastic lens over it that can accomodate lights up to 4" and establish a platform for the light to rest bezel down on and be completely exposed to allow a fan to keep it cool. I'll cut card board/paper templates for smaller lights that will allow perfect centering thus allowing consistent repeatable measurements. The other end w/the step down adapters will need to be sanded down to fit but will hold the light sensor.
Worst case is that if this doesn't work, since no glue or alteration is involved, I can return the 3 x 90deg. elbow which was the majority of the cost for this project. The step down adapters will need to be sanded down and can not be returned but I'm sure I cand find other uses for them.
I figure if I can establish a consistent X factor/multiplier, then it should be good enough. So do you guys think this will be reasonable to effectively measure lumens w/some degree of accuracy or is it just a pipe dream?